矩阵

\[\begin{bmatrix} a&c\\b&d \end{bmatrix} \begin{bmatrix}e&f\\g&h \end{bmatrix}=\begin{bmatrix}ae+cg&af+ch\\be+dg&bf+dh\end{bmatrix}\]

\[\begin{bmatrix}a&b&c\\d&e&f\\g&h&i\end{bmatrix}\begin{bmatrix}j&k&l\\m&n&o\\p&q&r\end{bmatrix}=\begin{bmatrix}a\times j+b\times m+c\times p&a\times k+b\times n+c\times q&a\times l+b\times o+c\times r\\d\times j+e\times m+f\times p&d\times k+e\times n+f\times q&d\times l+e\times o+f\times r\\a\times l+b\times o+c\times r&d\times l+e\times o+f\times r&g\times l+h\times o+i\times r\end{bmatrix} \]